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This week, on July 15, NASA's Aura satellite celebrated its 10th anniversary. Happy belated, Aura! The mission of Aura, which is Latin for breeze, centers on obtaining measurements of ozone, aerosols and key gases throughout the atmosphere. And after one decade in space, the satellite has provided vital data about the cause, concentrations and impact of major air pollutants.

The mission of Aura, which is Latin for breeze, centers on obtaining measurements of ozone, aerosols and key gases throughout the atmosphere. And after one decade in space, the satellite has provided vital data about the cause, concentrations and impact of major air pollutants.

One instrument on the satellite, built and managed by NASA's Jet Propulsion Laboratory is the Tropospheric Emission Spectrometer (TES). This instrument provides measurements of ozone and other greenhouse gases.

Near the ground, ozone can damages plants and can decrease lung function in humans. Somewhat higher in the atmosphere, ozone affects climate as a greenhouse gas. However, the majority of ozone is located in the stratosphere, 12 to 90 miles above the surface. This ozone is good because it shields us from the sun's ultraviolet light.

However, we have all heard about holes forming in the ozone, and over the Antarctic, cold temperatures and human-produced chlorine gases have been destroying ozone each spring. Scientists use Aura's Microwave Limb Sounder (MLS) instrument to measure ozone and other trace gases in and around the ozone hole every year. In 2006 and 2011, Aura's instruments revealed two of the largest and deepest ozone holes in the past decade, and also helped scientists understand the different causes of the two large holes.

Shortly after Aura's launch, the Ozone Monitoring Instrument (OMI) began monitoring levels of nitrogen dioxide, another major pollutant. This gas is an ingredient in ground-level ozone pollution. OMI data show that nitrogen dioxide levels in the United States decreased 4 percent per year from 2005 to 2010, a time when stricter policies on power plant and vehicle emissions came into effect. As a result, concentrations of ground-level ozone also decreased. During the same period, global nitrogen dioxide levels increased a little over half a percent per year whereas China's level increased about 6 percent per year.

"Pollution is a global issue because it can travel long distances in the wind," said Anne Douglass, Aura project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "By using satellites, we can develop a valuable global inventory of pollutants and understand how air quality may be changing."